1. Field
One or more embodiments relate to a microspeaker, and more particularly, to a micro-electro-mechanical systems (MEMS)-based piezoelectric microspeaker and a method of fabricating the same.
2. Description of the Related Art
The piezoelectric effect is the reversible conversion of mechanical energy into electrical energy using a piezoelectric material. In other words, the piezoelectric effect is a phenomenon in which a potential difference is generated when pressure or vibration is applied to a piezoelectric material, and the piezoelectric material deforms or vibrates when a potential difference is applied.
Piezoelectric speakers use the principle of applying a potential difference to a piezoelectric material to deform or vibrate the piezoelectric material and generating sound according to the vibration.
With the rapid progress of personal mobile communication, research on a subminiature acoustic transducer has been carried out for several decades. In particular, piezoelectric microspeakers have been researched due to their simple structures and ability to operate at low voltage.
In general, a piezoelectric microspeaker includes a piezoelectric plate on both sides of which electrode layers are formed, and a diaphragm which is not piezoelectric. When voltage is applied through the electrode layers, the piezoelectric plate is deformed, which causes the diaphragm to vibrate and generate sound.
However, since the piezoelectric microspeaker has a lower sound output level than a voice coil microspeaker, there are few cases of it being put to practical use. Thus, a piezoelectric microspeaker which has a small size and a high sound output level is needed.